Effect of natural ageing on the properties of recycled polypropylene/ethylene vinyl acetate/wood flour composites

Abstract

Wood flour composites main applications are represented by outdoor furnishing. Therefore, it is important to evaluate their behavior under natural ageing conditions. This work aims to investigate the natural ageing impact on the mechanical, physical, thermal e morphological properties of recycled polypropylene/ethylene vinyl acetate/wood flour composites (PP/EVA/ITA). Samples were exposed to natural ageing for 12 months in Porto Alegre (BR). Mezilaurus itauba (ITA) wood flour was used at 30 % w/w. Results showed that PP filled wood flour retained a higher fraction of the original mechanical properties after natural ageing. Crystallinity degree for composites increased from 30.9 up to 37.5% Climatic conditions affected the colorimetric and morphological characteristics of composites, indicating that there was not only photo-degradation but also thermo-oxidative and hydrolytic degradation. In this way, the use of antioxidant additives and UV photo-absorbers is recommended to avoid stress-cracking, discoloration and loss the mechanical properties.

Linear Low Density Polyethylene/Poly (Vinyl Alcohol)/Kenaf Composites: Effect of Natural Weathering on Functional Group, Weight Loss Characteristics, Tensile, Morphological and Thermal Properties

“…This leads to the deterioration in molecular weight and mechanical properties of the composites. The obtained results are in agreement with the earlier report by Nazrul Islam et al (2013), Silva et al (2017) and Zaaba et al (2015). Elongation at break is one of the most crucial tensile properties that are used when studying polymer degradation, as it can give an early indication of mechanical failure (Spinace & De Paoli 2015).…”

Influence of Coupling Agent in Mechanical, Physical and Thermal Properties of Polypropylene/Bamboo Fiber Composites: Under Natural Outdoor Aging

“…Figure 4a,b shows the thermogravimetric curves (TGA) and the derivatives of the thermogravimetric curves (DTG) respectively, of the composites before and after 12 months of exposure. It is observed that the composites presented four stages of mass loss, as follows: the first occurred below 100 °C and may be related to the humidity present in the fiber due to the hydrophilic It is observed that the composites presented four stages of mass loss, as follows: the first occurred below 100 • C and may be related to the humidity present in the fiber due to the hydrophilic characteristic, and probably due to some extractive substances with low molecular weight [43,44]; the second stage corresponds to the decomposition of the hemicellulose, in composites without CA with peak temperature of DTG at 259 • C before exposure and at 265 • C after exposure; in PP/BF/MA composites at 286 and 299 • C (before and after exposure respectively) and in PP/BF/CI composites at 295 and 289 • C (before and after exposure respectively). The third stage refers to the decomposition of the cellulose at 330 and 333 • C for the composites without CA (before and after exposure respectively), in composites PP/BF/MA at 348 and 357 • C (before and after exposure respectively) and in PP/BF/CI composites at a stable temperature of 357 • C before and after exposure.…”

Analysis and targeting of waste paper/polyester composites after weathering

“…No signs of cracks, warping and delamination were found on the surface of the composites after aging, but swelling (reaching 4.5 mm in thickness), texture variation, loss of gloss and surface yellowing were clear after exposure. For Twe & Liao (2003) and Silva et al (2017), these characteristics occur due to UV radiation, water absorption, degradation of the constituents and loss of interaction between them. Intensity of UV radiation in the material decreases as it moves away from the surface of UV penetration, being mostly a surface process.…”

“…And, in composites submitted to aging, the fiber/matrix interface is a critical region, where water can diffuse by capillarity. For lignocellulosic materials, which are hydrophilic, the oxidation reaction can be accelerated, reducing reinforcement/matrix adhesion by excess moisture (SILVA et al, 2017). Since the reinforcing material of this composite is paper, it easily absorbs water, creating hydrogen bonds and reducing interfacial interactions (AKIL et al, 2014).…”